How many miles per hour is 400 feet per second?
400 feet per second translates to 272.727273 miles per hour. 1 foot is actually equivalent to 0.000189393939 mile. A mile is simply defined as a unit of length.
Like 272-273 MPH..60x60x400 divided by the amount of feet in a mile(which I think is 5280..not sure though)